The present invention relates to a camera. More specifically this invention relates to a camera having power-saving mode.
Recently cameras such as video cameras or digital still cameras have a plurality of photographing modes so that both moving pictures and still images can be taken with a unit of camera. Such cameras have become more and more versatile and compatible with plurality types of recording media.
There is also the tendency that a screen size of a display device such as a liquid crystal display used for photographing images or replaying the photographed images has become increasingly larger for improving the user friendliness including easiness in use. Generally the display devices as described above display images not only during shooting but also in other operation modes, and therefore consume power even when the display devices are not being used for shooting.
When a camera with a battery incorporated therein is used for a long time, attention should be paid to power saving. For instance, it is necessary to turn off power when a camera is not used for shooting nor for setting. When power supply is switched from OFF to ON for shooting, a certain period of time is required until operations for shooting and recording are enabled, because it is necessary to perform several preparatory operations for enabling shooting and recording such as adjustment of an optical recording medium for read/write operations, checking of a capacity, and setting of a focus of the camera system. Therefore, when power supply is switched from OFF to ON, such operations as shooting and recording cannot be started immediately, and a photo opportunity may be lost. Cameras represented by video cameras and digital still cameras are always required to be kept in the state where shooting and recording can immediately be started, but if the power is always kept ON, the battery will be consumed soon, and in that case the camera cannot be used for a long period of time.
In the conventional technology, to solve the problems as described above, a drive unit required for recording is operated to assume the stand-by mode only when shooting is enabled by turning ON power for a video camera and setting the operation mode in the shooting mode for enabling shooting. In other words, when power is turned on, the drive unit is kept in the power-saving mode to suppress power consumption (Refer to Patent Document 1).
Other examples of conventional technology have a dedicated key (quick start key) for switching an operation mode of a video camera from the shooting mode, in which power is ON to the power-saving mode in which power consumption is suppressed as compared to that in the ordinary power ON state because displays on a liquid crystal display, a view finder and the like are not provided, and with this dedicated key shift to and from the power-saving mode can be performed. Furthermore, in the power-saving mode, the fact that the current operation mode is the power-saving mode is indicated by a light emitting device, so that a user can visually identify the current operation mode. Because of the configuration, when the operation mode is switched from the power-saving mode to the previous shooting mode in which power is turned on, a required operation can be started more quickly as compared to a case when the power OFF state is switched to the power ON state, which enables shortening of the time required until shooting is started. Video cameras having the quick start key have been put into the market (Refer to, for instance, Non-patent Document 1).
Patent document 2 includes the description of “With a power-saving switch 26 provided in a digital still camera, a user of the digital still camera can effect or release the power-saving mode according to the necessity. Furthermore the user can determine whether the current operation mode is the power-saving mode or not by visually checking a display state of the LED 21” (Abstract).
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-223929
[Patent Document 2]
Japanese Patent Laid-Open No. 2005-72808
[Non-patent Document 1]
Instruction Manual for Digital Video Camera “NV-GS250” produced by Matsushita Electric Industry Co., page 9, page 35.